U.S. patent application number 10/164049 was filed with the patent office on 2003-12-11 for fire-retardant fabric with improved tear, cut, and abrasion resistance.
Invention is credited to Young, Richard H., Zhu, Reiyao.
Application Number | 20030228821 10/164049 |
Document ID | / |
Family ID | 29710121 |
Filed Date | 2003-12-11 |
United States Patent
Application |
20030228821 |
Kind Code |
A1 |
Zhu, Reiyao ; et
al. |
December 11, 2003 |
Fire-retardant fabric with improved tear, cut, and abrasion
resistance
Abstract
A woven fabric useful in protective apparel made from yarn
components comprising a body fabric yarn component and a cut
resistant ripstop yarn component having at least 50% greater
tensile strength than the body fabric yarn component and comprising
a yarn having a synthetic staple-fiber sheath and inorganic core,
the body fabric yarn component and the cut resistant ripstop yarn
component both being comprised of at least one yarn and each yarn
component distinguished from the adjacent yarn component by
interweaving orthogonal yarn components.
Inventors: |
Zhu, Reiyao; (Midlothian,
VA) ; Young, Richard H.; (Richmond, VA) |
Correspondence
Address: |
E I DU PONT DE NEMOURS AND COMPANY
LEGAL PATENT RECORDS CENTER
BARLEY MILL PLAZA 25/1128
4417 LANCASTER PIKE
WILMINGTON
DE
19805
US
|
Family ID: |
29710121 |
Appl. No.: |
10/164049 |
Filed: |
June 6, 2002 |
Current U.S.
Class: |
442/197 ;
442/198; 442/217; 442/219; 442/220; 442/301 |
Current CPC
Class: |
D10B 2401/063 20130101;
Y10T 442/3309 20150401; Y10T 442/3976 20150401; D10B 2331/30
20130101; D10B 2501/04 20130101; D03D 1/0041 20130101; D02G 3/442
20130101; D03D 15/573 20210101; Y10T 442/3293 20150401; Y10T
442/313 20150401; D10B 2331/02 20130101; Y10T 442/3317 20150401;
D03D 15/49 20210101; A41D 31/24 20190201; D03D 15/25 20210101; D03D
15/47 20210101; Y10T 442/3138 20150401; A41D 31/08 20190201; D03D
15/513 20210101; D10B 2331/021 20130101; D02G 3/443 20130101; D03D
15/283 20210101 |
Class at
Publication: |
442/197 ;
442/217; 442/220; 442/219; 442/301; 442/198 |
International
Class: |
B32B 005/08; B32B
017/02; D03D 015/00 |
Claims
What is claimed is:
1. A woven fabric useful in protective apparel made from yarn
components comprising: a body fabric yarn component, a ripstop yarn
component comprising a cut resistant yarn having a synthetic
staple-fiber sheath and inorganic core, said ripstop yarn component
having at least 50% greater tensile strength than the body fabric
yarn component, the body fabric yarn component and the ripstop yarn
component being comprised of at least one yarn and each yarn
component distinguished from the adjacent yarn component by
interweaving orthogonal yarn components.
2. The woven fabric of claim 1 wherein the ripstop yarn component
comprises a textured or bulked continuous filament yarn.
3. The woven fabric of claim 1 wherein the ripstop yarn component
comprises poly (p-phenylene terephthalamide) fibers.
4. The woven fabric of claim 1 wherein the ripstop yarn component
comprises fire-resistant fibers.
5. The woven fabric of claim 4 wherein the ripstop yarn component
comprises, in addition to fire-resistant fibers, nylon fibers in an
amount of up to 20% by weight of the ripstop yarn component
6. The woven fabric of claim 1 wherein the staple-fiber sheath
comprises staple fibers are made from poly (p-phenylene
terephthalamide) and the inorganic core comprises metal fiber.
7. The woven fabric of claim 1 wherein the ripstop yarn component
comprises cut resistant fibers.
8. The woven fabric of claim 7 wherein the ripstop yarn component
comprises, in addition to the cut resistant fibers, nylon fibers in
an amount of up to 20% by weight of the ripstop yarn component
yarn.
9. The fabric of claim 1 wherein the body fabric component
comprises yarns of fire-resistant fibers.
10. The woven fabric of claim 9 wherein the body fabric yarn
component yarn comprises, in addition to fire-resistant fibers,
nylon fibers in an amount of up to 20% by weight of the body fabric
yarn.
11. A woven fabric useful in protective apparel made from yarn
components comprising: a) a body fabric yarn component, b) a
ripstop yarn component comprising a cut resistant yarn having a
synthetic staple-fiber sheath and inorganic core, said ripstop yarn
component having at least 50% greater tensile strength than the
body fabric yarn component, the body fabric yarn component and the
ripstop yarn component being comprised of individual or plied warp
and fill yarns in the fabric, and wherein every fifth to ninth
orthogonal warp and fill yarn component is a ripstop yarn
component.
12. The woven fabric of claim 11 wherein the ripstop yarn component
comprises a textured or bulked continuous filament yarn.
13. A process for making a woven fabric useful in protective
apparel made from warp and fill yarn components comprising: a)
weaving a fabric from a body fabric yarn component, and b)
inserting into the weave at every fifth to ninth warp and fill
component a ripstop yarn component comprising a cut resistant yarn
having a synthetic staple-fiber sheath and inorganic core, said
ripstop yarn component having at least 50% greater tensile strength
than the body fabric yarn component.
14. The process of claim 13 wherein the ripstop yarn component is
assembled, prior to insertion into the weave, by including, in
addition to the cut resistant yarn, a textured or bulked continuous
filament yarn.
15. A process for making a woven fabric useful in protective
apparel made from warp and fill yarn components comprising: a)
weaving a fabric from a body fabric yarn component, and b)
inserting into the weave at every fifth to ninth warp and fill
component a ripstop yarn component to create an array of cut
resistant ripstop yarn components, each component comprising a cut
resistant yarn having a synthetic staple-fiber sheath and inorganic
core, said ripstop yarn component having at least 50% greater
tensile strength than the body fabric yarn component.
16. The process of claim 15 wherein the ripstop yarn component is
assembled, prior to insertion into the weave, by including, in
addition to the cut resistant yarn, a textured or bulked continuous
filament yarn.
Description
BACKGROUND OF THE INVENTION
[0001] This invention relates to fabrics useful in protective
garments, especially garments known as turnout gear which are
useful for firefighters, but such fabrics and garments also have
use in industrial applications where workers may be exposed to
abrasive and mechanically harsh environments where fire and flame
protection is needed. The garments, which include coats, coveralls,
jackets, and/or pants can provide protection against fire, flame,
and heat.
[0002] Most turnout gear commonly used by firefighters in the
United States comprise three layers, each performing a distinct
function. There is an outer shell fabric often made from flame
resistant aramid fiber such as poly (meta-phenylene iosphthalamide)
(MPD-I) or poly (para-phenylene terephthalamide) (PPD-T) or blends
of those fibers with flame resistant fibers such as
polybenzimidazoles (PBI). Adjacent to the outer shell fabric is a
moisture barrier and common moisture barriers include a laminate of
Crosstech.RTM. PTFE membrane on a woven MPD-I/PPD-T substrate, or a
laminate of neoprene on a fibrous woven polyester/cotton substrate.
Adjacent the moisture barrier is an insulating thermal liner which
generally comprises a batt of heat resistant fiber.
[0003] The outer shell serves as initial flame protection while the
thermal liner and moisture barrier protect against heat stress.
[0004] Since the outer shell provides primary defense it is
desirable that this shell be durable and able to withstand abrasion
and not tear or be cut in harsh environments. This invention
provides for such a fabric that is flame resistant and has improved
tear, cut, and abrasion attributes.
[0005] There are a number of fabrics described in the prior art
which utilize bare steel wires and cords, primarily as armored
fabrics. For example, WO 9727769 (Bourgois et al.) discloses a
protective textile fabric comprising a plurality of steel cords
twisted together. WO 200186046 (Vanassche et al.) discloses a
fabric comprising steel elements used to provide cut resistance or
reinforcement for protective textiles. The steel elements are
either a single steel wire, a bundle of non-twisted steel wires, or
a cord of twisted steel fibers. GB 2324100 (Soar) discloses a
protective material made from twisted multi-strand cable which may
be stitched to one or more layers of Kevlar.RTM. to form a unitary
material. The use of bare metal wire presents processing challenges
and garment aesthetic (comfort and feel) problems and is
undesirable.
[0006] U.S. Pat. No. 4,470,251 (Bettcher) discloses a cut resistant
yarn made by winding a number of synthetic fibers yarns, such as
nylon and aramid, around a core of strands of stainless steel wire
and a high strength synthetic fiber such as aramid, and a safety
garment made from the wound yarn.
[0007] U.S. Pat. No. 5,119,512 (Dunbar et al.) discloses a
protective fabric made from cut resistant yarn comprising two
dissimilar non-metallic fibers, at least one being flexible and
inherently cut resistant and the other having a level of hardness
at above three Mohs on the hardness scale.
SUMMARY OF THE INVENTION
[0008] The present invention is directed to a woven fabric useful
in protective apparel made from yarn components comprising a body
fabric yarn component and a cut resistant ripstop yarn component,
the cut resistant ripstop yarn component comprising a cut resistant
yarn having a synthetic staple-fiber sheath and inorganic core, the
ripstop yarn component having at least 50% greater tensile strength
than the body fabric yarn component, the body fabric yarn component
and the ripstop yarn component each being comprised of at least one
yarn and each yarn component distinguished from the adjacent yarn
component by interweaving orthogonal yarn components. The
staple-fiber sheath of the cut resistant yarn of the ripstop yarn
component preferably comprises staple fibers that are made from
poly (p-phenylene terephthalamide) and the inorganic core comprises
preferably metal fiber. The cut resistant ripstop yarn component
can also contain a textured or bulked continuous filament yarn. The
cut resistant ripstop yarn component preferably contains fibers
that are both cut resistant and fire resistant, and the preferred
fiber having both of these qualities is poly (p-phenylene
terephthalamide) fiber. In addition, the cut resistant ripstop yarn
component may contain nylon fibers in an amount of up to 20% by
weight of the ripstop yarn component. The body fabric component of
this invention comprises yarns of fire-resistant fibers, and
preferably comprises, in addition to fire-resistant fibers, nylon
fibers in an amount of up to 20% by weight of the body fabric yarn
component.
[0009] One embodiment of this invention is directed to a woven
fabric useful in protective apparel made from yarn components
comprising a body fabric yarn component and a cut resistant ripstop
yarn component comprising a cut resistant yarn having a synthetic
staple-fiber sheath and inorganic core, the cut resistant ripstop
yarn component having at least 50% greater tensile strength than
the body fabric yarn component; the body fabric yarn component and
the cut resistant ripstop yarn component being comprised of
individual or plied warp and fill yarns in the fabric, and wherein
every fifth to ninth orthogonal warp and fill yarn component is a
cut resistant ripstop yarn component. Further, the cut resistant
ripstop yarn component can contain a textured or bulked continuous
filament yarn.
[0010] This invention is also directed to a process for making a
woven fabric useful in protective apparel made from warp and fill
yarn components comprising weaving a fabric from a body fabric yarn
component, and inserting into the weave at every fifth to ninth
warp and/or fill component a cut resistant ripstop yarn component
comprising a cut resistant yarn having a synthetic staple-fiber
sheath and inorganic core, said ripstop yarn component having at
least 50% greater tensile strength than the body fabric yarn
component.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] FIG. 1 is an illustration of some of the possible yarn
components in the fill direction separated by interweaving
orthogonal warp yarn components in the fabric of this
invention.
[0012] FIG. 2 is illustration of a cut resistant yarn having a
staple fiber sheath/and inorganic core construction.
[0013] FIG. 3 is an illustration of one embodiment of the fabric of
this invention.
[0014] FIG. 4 is an illustration of another embodiment of the
fabric of this invention.
DETAILED DESCRIPTION OF THE INVENTION
[0015] The fabrics of this invention have in combination improved
cut resistance and improved tear resistance over prior art fabrics
and preferably have improved abrasion resistance. The fabrics are
woven using known machines for weaving fabric and can be
incorporated into protective apparel and garments of various types.
These fabrics typically weigh in the range of 4 to 12 ounces per
square yard and can be any orthogonal weave, however plain weave
and 2.times.1 twill weave are the preferred weaves.
[0016] This invention comprises two types of yarn components, a
body fabric yarn component and a cut resistant ripstop yarn
component having incorporated therein a cut resistant yarn. As
referred to herein, a yarn component can be a yarn, a plied yarn,
or a combination of yarns or a combination of plied yarns. In
general, each yarn component lying in one direction of a woven
fabric is distinguished from the adjacent yarn component in that
same direction by interweaving orthogonal yarn components. In a
plain weave, for example, the warp and fill yarn components are
interwoven wherein the warp yarn components go over and under the
fill yarn components, delineating each fill yarn component and
distinguishing it from the adjacent fill yarn component. Likewise,
adjacent warp yarn components alternate the direction of the
interweave with the fill yarn; that is, a first warp yarn component
will go over a fill yarn component and a second adjacent warp yarn
component will go under that same fill yarn component. This
alternate interweaving action is duplicated throughout the fabric
creating the classic plain weave structure. Therefore, the fill
yarn components also delineate each warp yarn component from
adjacent warp yarn components. In a twill weave, the warp and fill
yarn components are interpreted the same even though there is less
actual interweaving of warp and fill yarn components. In a
2.times.1 twill weave, the offset staggered interweaving structure
of that weave means a warp yarn component passes over more than one
fill yarn component and lies directly adjacent to another warp yarn
component periodically in the fabric. However, the warp and fill
yarn components are still delineated by each other even if they are
offset or staggered in the fabric, and the yarn components can be
clearly identified by inspection.
[0017] Typically, the major portion of the fabric is made from body
fabric yarn components and these components normally comprise yarns
containing fire-resistant fibers. The term "fire resistance fibers"
as used herein means staple or filament fibers of polymers
containing both carbon and hydrogen and which may also contain
other elements such as oxygen and nitrogen, and which have a LOI 25
and above. Suitable fire-resistant fibers include poly
(meta-phenylene isophthalamide) (MPD-I), poly (para-phenylene
terephthalamide) (PPD-T), polybenzimidazoles (PBI), poly-phenylene
benzobisoxazole (PBO), and/or blends or mixtures of those fibers.
For improved abrasion resistance, the body fabric yarn components
can have in addition to the fire-resistant fibers up to 20 percent
by weight nylon fibers, preferably less than 10 percent by weight.
The body fabric yarn components are preferably staple yarns
containing 60 weight percent PPD-T fiber and 40 weight percent PBI
fiber. The preferred form and size of the body fabric yarn
component is a plied yarn of the above composition having a cotton
count in the range of 16/2 to 21/2.
[0018] The cut-resistant ripstop yarn component of the fabric is
useful in providing both cut resistance and tear strength to the
fabric and has a tensile strength which is at least 50% greater
than the tensile strength of a body fabric yarn component. The cut
resistant ripstop yarn component contains at least one cut
resistant yarn having a synthetic staple fiber sheath and an
inorganic core and can also contain, in addition, continuous
synthetic multifilament yarn. It is preferred that the cut
resistant ripstop yarn component contain fibers which are
fire-resistant. Suitable fire-resistant fibers include those made
from aramids such as poly (para-phenylene terephthalamide) (PPD-T),
poly(meta-phenylene isophthalamide) (MPD-I), and other high
strength polymers such as poly-phenylene benzobisoxazole (PBO)
and/or blends or mixtures of those fibers. The cut resistant
ripstop yarn component preferably contains 1 to 3 continuous
filament yarns. If one yarn is used for the cut resistant ripstop
yarn component, that one yarn must have at least 50% greater
tensile strength than the tensile strength of a body fabric yarn
component; if three yarns are used for the cut resistant ripstop
yarn component, then the combined three yarns must have a tensile
strength of at least 50% or greater than that of the body fabric
component. If more than one yarn is used as the cut resistant
ripstop yarn component, the yarns may be plied together or may be
used without plying. The total denier of the cut resistant ripstop
yarn component is in the range of 200 denier to 1500 denier and the
denier of continuous filament yarns suitable for use in the cut
resistant ripstop yarn component is in the range of 200-1000
denier. The cut resistant ripstop yarn component can also have,
combined with or in addition to the fire-resistant yarn, up to 20
percent nylon fiber for improve abrasion resistance.
[0019] The cut resistant ripstop yarn component of the fabric of
this invention contains at least one yarn having a sheath/core
construction wherein the sheath comprises synthetic fibers and the
core comprises inorganic fibers. The fibers in the sheath are
comprised of synthetic staple fibers for they create a more
comfortable yarn. Preferably, the synthetic fibers in the sheath
comprises cut resistant fibers, which can include any number of
fibers made from poly (para-phenylene terephthalamide) (PPD-T) and
other high strength polymers such as poly-phenylene benzobisoxazole
(PBO) and mixtures or blends thereof. It is preferred that that the
cut resistant fibers also be fire resistant and the preferred fire
retardant and cut resistant fiber is PPD-T fiber. The sheath can
also include some fibers of other materials to the extent that
decreased cut resistance, due to that other material, can be
tolerated. The cut resistant yarn component can also have, combined
with or in addition to the cut resistant fibers, up to 20 percent
by weight nylon fiber for improved abrasion resistance.
[0020] The core of the sheath/core yarn contains at least one
inorganic fiber. Inorganic fibers useful in the core include glass
fiber or fibers made from metal or metal alloys. The metal fiber
core can be a single metal fiber or several metal fibers, as needed
or desired for a particular situation. The preferred core fiber is
a single metal fiber made from stainless steel. By metal fibers is
meant fibers or wire made from a ductile metal such as stainless
steel, copper, aluminum, bronze, and the like. The metal fibers are
generally continuous wires and are 10 to 150 micrometers in
diameter, and are preferably 25 to 75 micrometers in diameter.
[0021] The staple fibers comprising the sheath can be wrapped or
spun around metal fiber core. If wrapped, the staple fibers are
generally in the form of staple fibers loosely consolidated or spun
by known means, such as, ring spinning, wrap spinning, air-jet
spinning, open-end spinning, and the like; and then wound around
the metal core at a density sufficient to substantially cover the
core. If spun, the staple fiber sheath is formed directly over
metal fiber core by any appropriate sheath/core-spinning process
such as DREF spinning or so-called Murata jet spinning or another
core spinning process. The fire retardant PPD-T staple fibers
present in the sheath have a diameter of 5 to 25 micrometers and
may have a length of 2 to 20 centimeters, preferably 4 to 6
centimeters. Once the staple fibers are wrapped or spun around the
core, these sheath/core yarns having the preferred metal fiber core
are generally 1 to 50 weight percent metal with a total linear
density of 100 to 5000 dtex.
[0022] FIG. 2 is an illustration of a cut resistant yarn 7 that may
be used in the cut resistant ripstop yarn component of this
invention. The yarn has a staple fiber sheath 9 that is disposed
around an inorganic core fiber 8. The cut resistant ripstop yarn
component of this fabric can be made from a combination of plied
yarns, although only one of the yarns in this combination of plied
yarns is required to have the sheath/core construction. For
example, if the cut resistant yarn component is to have three
yarns, these three yarns can be twisted or plied about each other
to form a plied yarn. However, only one of the three yarns is
required to have the sheath/core construction. Likewise, for
example, if the cut resistant yarn component is to have four yarns,
these four yarns can be paired and then twisted or plied about each
other to form two plied yarns. However, only one of the four yarns
is required to have the sheath/core construction. Plied yarns are
yarns that are brought together with only a small amount of twist,
normally in the range of 5 to 10 turns or twists per inch. This low
amount of twisting provides for a consolidated and balanced yarn
without totally covering or wrapping one yarn with the other
yarn.
[0023] The remaining yarns in the cut resistant ripstop yarn
component can have almost any construction, but it is desired that
they be comprised of predominantly fire resistant materials so as
to maintain the fire resistant nature of the garment. Specifically,
these remaining yarns can be made from aramid staple fibers or
continuous aramid filaments, and may contain other fibers and
materials. However, it must be recognized the fire retardancy
and/or cut resistance of the fabric may be diminished by the
presence of such other materials. Typically, these remaining yarns
can have a linear density in the range of 200 to 2000 dtex and the
individual filaments or fibers have a linear density of 0.5 to 7
dtex, preferably 1.5 to 3 dtex.
[0024] The preferred construction of the cut resistant yarn used in
the cut resistant ripstop yarn component is a plied yarn made from
two sheath/core yarns wherein for each yarn the sheath is staple
fiber PPD-T having a cut length of 48 mm (1.89) and the core is a
1.5 mil diameter stainless steel filament. The preferred yarn has a
cotton count sizing of 16/2 to 21/2 (664 - 465 denier). Optionally,
the sheath/core yarns may have in addition to the fire retardant
cut resistant fiber in the sheath up to 10 weight percent and as
much as 20 weight percent nylon, based on the weight of the sheath
fiber, to provide improved abrasion resistance.
[0025] If the cut resistant ripstop yarn component contains a
continuous synthetic multifilament yarn, that yarn preferably is a
textured or bulked continuous filament yarn, and the preferred
fiber for that yarn is 600 denier PPD-T fiber having a linear
density of 1.5 dpf. The continuous multifilament yarn used in the
cut resistant ripstop yarn component is textured or bulked to
co-mingle the filaments and create a random entangled loop
structure in the yarn. One process known in the art which
accomplishes this is called air-jet texturing wherein pressurized
air, or some other fluid, is used to rearrange the filament bundle
and create loops and bows along the length of the yarn. In a
typical process, the multi-filament yarn to be bulked is fed to a
texturing nozzle at a greater rate than it is removed from the
nozzle. The pressurized air impacts the filament bundle, creating
loops and entangling the filaments in a random manner. For the
purposes of this invention, it is desirable to have an overfeed
rate of 14 to 25% with a usable range in the order of 5 to 30%.
Using a bulking process with this overfeed rate creates a
co-mingled yarn having a higher weight per unit length, or denier,
than the yarn that was fed to the texturing nozzle. It has been
found that the increase in weight per unit length should be in the
range of 3 to 25 weight percent, with increases in the 10 to 18
weight percent preferred. It has been found that the bulked yarn
that is most useful in the making of the fabric in this invention
is preferably in the range of 200 to 1000 denier, and more
preferably 300 to 600 denier. The loops and entanglements create a
continuous filament yarn which has some surface characteristics
similar to a spun staple yarn.
[0026] FIG. 1 is a very simplified illustration of some of the
possible fill yarn components separated by interweaving orthogonal
warp yarn components. Body yarn components 1 made from, for
example, a collection of staple yarns, are shown separated from
such things as other body yarn components and cut resistant ripstop
yarn components 3 by the interweaving warp yarn component 6. A
possible cut resistant yarn ripstop component 3 is shown having the
preferred combination of types of yarns, namely textured continuous
filament yarns and a plied yarn made from two staple
sheath/inorganic core cut resistant yarns, with the inorganic core
shown in those yarns not to scale but magnified for illustration
purposes. The body fabric yarn component 1 can be made up from a
combination of single yarns and/or plied yarns. Similar types of
yarn components can be, and preferably are, present in the warp
direction.
[0027] The woven fabric of this invention typically has a
predominance of body fabric yarn components with only enough of the
cut resistant ripstop yarn components to allow the fabric to
perform in the fabric's intended use. It is desirable to have cut
resistant ripstop yarn components in both the warp and fill
directions. Further, it is desired to uniformly distribute the cut
resistant ripstop yarn components throughout the fabric in both the
warp and fill directions so that the durability imparted by the cut
resistant ripstop yarn component is uniform across the fabric.
Further, it is believed that the most useful fabrics are made when
the cut resistant ripstop yarn component is distributed in the
fabric as every fifth to ninth orthogonal warp and fill yarn
component in the fabric, with the preferred spacing having a cut
resistant ripstop yarn component every seventh warp and fill yarn
component. If a high proportion of the body fabric yarn components
are made from staple yarns, it will be desirable to bulk or texture
any continuous filaments used in the ripstop yarn component. FIG. 3
is an illustration of one embodiment of the fabric of this
invention with the warp and fill yarn components shown broadly
separated and simplified for illustration purposes. Cut resistant
ripstop yarn components 10 are shown in both the warp and fill and
are present as every eighth component in the fabric. Body fabric
yarn components 11 are shown in both the warp and fill between the
cut resistant ripstop yarn components.
[0028] In another embodiment of this invention, the woven fabric of
this invention is made from body fabric yarn components and cut
resistant ripstop yarn components wherein each cut resistant
ripstop yarn component has at least 50% greater tensile strength
than each body fabric yarn component, the cut resistant ripstop
yarn component comprises a yarn having a synthetic staple-fiber
sheath and an inorganic core, and the cut resistant ripstop yarn
components are present in only the warp or the fill of the fabric.
The cut resistant ripstop yarn component can also contain
continuous multifilament yarn which may be textured or bulked. FIG.
4 is an illustration of this type of fabric. The cut resistant
ripstop yarn components 10 are shown only in the warp direction and
all other warp yarns are body fabric yarn components 11. The yarn
components shown in the fill direction are all body fabric yarn
components 11.
[0029] This invention is also directed to a process for making the
fabric of this invention comprising weaving a fabric from a body
fabric yarn component and inserting into the weave at every fifth
to ninth warp and fill component a cut resistant ripstop yarn
component comprising a yarn having synthetic staple fiber sheath
and an inorganic core said cut resistant yarn component having at
least 50% greater strength than the body fabric yarn component.
[0030] Another embodiment of the process for making the woven
fabric of this invention having orthogonal yarn components involves
weaving a fabric from a body fabric yarn component, inserting into
the weave at every fifth to ninth yarn component a cut resistant
ripstop yarn component, creating a parallel array of those
components in the fabric, each component comprising a yarn having
synthetic staple fiber sheath and an inorganic core and each
component having at least 50% greater tensile strength than the
body fabric yarn component.
[0031] The fabrics of this invention are useful in and can be
incorporated into protective garments, especially garments known as
turnout gear which are useful for firefighters. These garments also
have use in industrial applications where workers may be exposed to
abrasive and mechanically harsh environments where fire and flame
protection is needed. The garments, may include coats, coveralls,
jackets, pants, sleeves, aprons, and other types of apparel where
protection against fire, flame, and heat is needed.
TEST METHODS
Thermal Protective Performance Test (TPP)
[0032] The predicted protective performance of a fabric in heat and
flame was measured using the "Thermal Protective Performance Test"
NFPA 2112. A flame was directed at a section of fabric mounted in a
horizontal position at a specified heat flux (typically 84
kW/m.sup.2). The test measures the transmitted heat energy from the
source through the specimen using a copper slug calorimeter and
there is no space between fabric and heat source. The test endpoint
is characterized by the time required to attain a predicted
second-degree skin burn injury using a simplified model developed
by Stoll & Chianta, "Transactions New York Academy Science",
1971,33 p649-670. The value assigned to a specimen in this test,
denoted as the TPP value, is the total heat energy required to
attain the endpoint, or the direct heat source exposure time to the
predicted burn injury multiplied by the incident heat flux. Higher
TPP values denote better insulation performance. A three layer
testing sample is prepared consisting of outer shell fabric
(current invention), a moisture barrier and a thermal liner. The
moisture barrier was Crosstech.RTM. attached to a 2.7 oz/yd.sup.2
(92 grams/square meter) Nomex.RTM./Kevlar.RTM. fiber substrate and
the thermal liner consisted of three spunlaced 1.5 oz/yd.sup.2 (51
grams/square meter) sheets quilted to a 3.2 oz/yd.sup.2 (108
grams/square meter) Nomex.RTM. staple fiber scrim.
Abrasion Resistance Test
[0033] Abrasion resistance was determined using ASTM method
D3884-80, with a H-18 wheel, 500 gms load on a Taber abrasion
resistance available from Teledyne Taber, 455 Bryant St., North
Tonawanda, N.Y. 14120. Taber abrasion resistance is reported as
cycles to failure.
Cut Resistance Test
[0034] Cut resistance was measured using the "Standard Test Method
for Measuring Cut Resistance of Materials Used in Protective
Clothing", ASTM Standard F 1790-97. In performance of the test, a
cutting edge, under specified force, was drawn one time across a
sample mounted on a mandrel. At several different forces, the
distance drawn from initial contact to cut through was recorded and
a graph constructed of force as a function of distance to cut
through. From the graph, the force was determined for cut through
at a distance of 25 millimeters and was normalized to validate the
consistency of the blade supply. The normalized force was reported
as the cut resistance force. The cutting edge was a stainless steel
knife blade having a sharp edge 70 millimeters long. The blade
supply was calibrated by using a load of 400 g on a neoprene
calibration material at the beginning and end of the test. A new
cutting edge was used for each cut test. The sample was a
rectangular piece of fabric cut 50.times.100 millimeters on the
bias at 45 degrees from the warp and fill directions. The mandrel
was a rounded electrical conductive bar with a radius of 38
millimeters and the sample was mounted thereto using double-face
tape. The cutting edge was drawn across the fabric on the mandrel
at a right angle with the longitudinal axis of the mandrel. Cut
through was recorded when the cutting edge makes electrical contact
with the mandrel.
Tear Strength Test
[0035] The tear strength measurement is based on ASTM D 5587-96.
This test method covers the measurement of the tear strength of
textile fabrics by the trapezoid procedure using a recording
constant-rate-of-extension-type (CRE) tensile testing machine. Tear
strength, as measured in this test method, requires that the tear
be initiated before testing. The specimen was slit at the center of
the smallest base of the trapezoid to start the tear. The
nonparallel sides of the marked trapezoid were clamped in parallel
jaws of a tensile testing machine. The separation of the jaws was
increased continuously to apply a force to propagate the tear
across the specimen. At the same time, the force developed was
recorded. The force to continue the tear was calculated from
autographic chart recorders or microprocessor data collection
systems. Two calculations for trapezoid tearing strength were
provided: the single-peak force and the average of five highest
peak forces. For the examples of this patent, the single-peak force
is used.
Grab Strength Test
[0036] The grab strength measurement, which is a determination of
breaking strength and elongation of fabric or other sheet
materials, is based on ASTM D5034. A 100-mm (4.0 in.) wide specimen
is mounted centrally in clamps of a tensile testing machine and a
force applied until the specimen breaks. Values for the breaking
force and the elongation of the test specimen are obtained from
machine scales or a computer interfaced with testing machine.
EXAMPLES
EXAMPLE 1
[0037] This example illustrates the fabric of this invention
utilizing a cut resistant ripstop yarn component containing a cut
resistant yarn having a stainless steel wire core and a PPD-T
/nylon staple fiber sheath. The staple fiber sheath was a blend of
90 weight percent PPD-T staple fiber (Kevlar.RTM. fiber 1.5 dpf, 48
mm (1.89 inch) available from E. I. du Pont de Nemours & Co.,
Inc.) and 10 weight percent nylon staple fiber (Nylon type T200,
1.1 dpf and 38mm (1.5 inch) available from E. I. du Pont de Nemours
& Co., Inc. The steel wire was 1.5 mil in diameter.
[0038] The PPD-T and nylon fibers were fed through a standard
carding machine used in the processing of short staple ring spun
yarns to make carded sliver. The carded sliver was processed using
two pass drawing (breaker/finisher drawing) into drawn sliver and
processed on a roving frame to make a one hank roving. The roving
was then fed into spinning frame with steel wire to form a
sheath/core yarn structure. Sheath-core strands were produced by
ring-spinning two ends of the roving and inserting the steel core
just prior to twisting. The roving was about 5900 dtex (1 hank
count). In this example, the steel core was centered between the
two drawn roving ends just prior to the final draft rollers. 16/1
cc strands were produced using a 3.5 twist multiplier for each
item. The single strand of 16/1 cc is then plied to 16/2 cc to form
a stable yarn for further weaving process.
[0039] A commercially available ring-spun yarn containing PPD-T and
PBI fiber (1.5 dpf, 51 mm (2 inch)) having those fibers present in
a 60/40 blending ratio was obtained from Pharr Yarns, Inc., of 100
Main Street, McAdenville, N.C., for use in the body fabric yarn
component.
[0040] A 5/2 cut resistant ripstop plain weave fabric was made,
wherein the cut resistant ripstop yarn component (CRRYC) was 2
yarns of the sheath/core PPD-T/nylon and steel yarn mentioned above
plied together. Each body fabric yarn component (BFYC) contained
one of the PPD-T/PBI plied yarns. In the warp and fill, for the 5/2
construction was CRRYC /BFYC/BFYC/BFYC/BFYC/BFYC/CRRYC. The fabric
is then heated in oven at 265C. for 5 mins. The heat treatment
caused the nylon to shrink to further improve the abrasion
resistance of the fabric.
EXAMPLE 2
[0041] In this example, a highly wear resistant and cut resistant
plain weave fabric for thermal protection was prepared. PPD-T, PBI
and nylon staple fiber identical to those used in Example 1 were
blended in percentages of 50%, 40% and 10%, respectively, and were
fed through a standard carding machine used in the processing of
short staple ring spun yarns to make carded sliver. The carded
sliver was processed using two pass drawing (breaker/finisher
drawing) into drawn sliver and processed on a roving frame to make
a one hank roving. The roving was then fed into spinning frame. The
roving was about 5900 dtex (1 hank count). 16/1 cc strands were
produced using a 3.5 twist multiplier for each item. The single
strand of 16/1 cc is then plied to 16/2 cc to form a stable yarn
for further weaving process. These plied yarns became the body
fabric yarn components in the fabric. Each body fabric yarn
component contained one of the plied yarns.
[0042] The cut resistant ripstop component was made from one cut
resistant yarn of PPD-T/nylon staple fiber sheath and a stainless
steel wire core, same as example 1, along with one yarn of 600
denier textured PPD-T continuous filament yarn.
[0043] The 7.times.2 ripstop plain weave fabric was made from these
two components, where the body of plain weave area was made from
the body fabric yarn components, while every 8.sup.th warp and fill
component a cut resistant ripstop yarn component was inserted. The
resulted fabric had high strength, cut and abrasion resistance.
1TABLE 1 The testing results of the various fabric samples Example
2 7 body yarn components of Kevlar/PBI/nylon Example 1 blend in 5
body yarn plain weave components of and 1 end of Kevlar/PBI blend
stainless Steel Standard in plain weave wrapped with Kevlar
.RTM./PBI and 2 ends of Kevlar-nylon Kevlar .RTM./PBI stainless
Steel and 1 end of blend with wrapped with 600 textured double ends
Kevlar-nylon in Kevlar .RTM. in ripstop ripstop in ripstop Test
Type component component component Basis Wt. 257.6 264.4 267.8
(g/m2) Thickness 0.66 0.89 1.22 (mm) Trap Tear 13.1 .times. 12.3
16.3 .times. 15.9 32.2 .times. 31.3 (warp .times. fill kg) Grab
Strength 119.4 .times. 105.3 114 .times. 117.1 116.2 .times. 96.7
(warp .times. fill kg) Abrasion 184 193 280.6 (cycles) Cut
Resistance 469 1251 788 (g) TPP (cal/cm{circumflex over ( )}2) 42
48 41.2
* * * * *